Develop Reference

Pandas create a new sheet instead of adding the data in the active one

I am creating a spreadsheet with openpyxl and adding some data.
import pandas as pd
import numpy as np
from openpyxl import Workbook
from openpyxl.utils.dataframe import dataframe_to_rows
from openpyxl import load_workbook
from collections import OrderedDict
workbook = Workbook()
sheet = workbook.active
def fill_static_values():
sheet["A1"] = "Run No."
sheet["A2"] = "MLIDMLPA"
sheet["A48"] = "Patients here"
sheet["B1"] = "Patient"
fill_static_values()
output = "./Name_of_run.xlsx"
workbook.save(filename=output)
Then my application do some data management and I want to add some of this data into the existing file.
book = load_workbook(output)
writer = pd.ExcelWriter(output, engine='openpyxl')
writer.book = book
## ExcelWriter for some reason uses writer.sheets to access the sheet.
## If you leave it empty it will not know that sheet Main is already there
## and will create a new sheet.
writer.sheets = dict((ws.title, ws) for ws in book.worksheets)
data_no_control.to_excel(writer, "sheet", startrow=2, startcol=3,
header=False,
index=False)
writer.save()
Solution found on this StackOverflow link
However, this is creating and adding the data in the correct position but in a new sheet called sheet2. What I am doing wrong?

The to_excel has incorrect sheet name. The S should be in CAPS. Change the line from
data_no_control.to_excel(writer, "sheet", startrow=2, startcol=3,
to
data_no_control.to_excel(writer, "Sheet", startrow=2, startcol=3,
As there is already a sheet in the excel, it is writing the data to Sheet2
EDIT
Noticed that you are using writer.sheets. If you want to use want the program pick up the first sheet from excel automatically, you can use this as well...
data_no_control.to_excel(writer, sheet_name=list(writer.sheets.keys())[0], startrow=2, startcol=3,
This will pick up the first sheet (in your case the only sheet) as the worksheet to update

Appending to a sheet in Excel creates a new sheet instead of appending

I am trying to use this code to append a dataframe to an existing sheet in Excel, but instead of appending the new data to it, it creates a new sheet. Here is the code:
import pandas as pd
import openpyxl as op
df = ['normal_dataframe']
with pd.ExcelWriter('test.xlsx', engine='openpyxl', mode='a') as writer:
df.to_excel(writer, sheet_name='Sheet1', header=False, index=False)
'test.xlsx' has a 'Sheet1', but when the file is appended, theres 2 sheets. 'Sheet1' and 'Sheet11'.

One approach with COM:
import win32com.client
xl = win32com.client.Dispatch("Excel.Application")
path = r'c:\Users\Alex20\Documents\test.xlsx'
wb = xl.Workbooks.Open(path)
ws = wb.Worksheets("Sheet1")
ws.Range("E9:F10").Value = [[9,9],[10,10]]
wb.Close(True)
xl.Quit()

Creating a Master excel file from dynamic CSV output using Python

I am trying to create a repository "Master" excel file from a CSV which will be generated and overwritten every couple of hours. The code below creates a new excel file and writes the content from "combo1.csv" to "master.xlsx". However, whenever the combo1 file is updated, the code basically overwrites the contents in the "master.xlsx" file. I need to append the contents from "combo1" to "Master" without the headers being inserted every time. Can someone help me with this?
import pandas as pd
writer = pd.ExcelWriter('master.xlsx', engine='xlsxwriter')
df = pd.read_csv('combo1.csv')
df.to_excel(writer, sheet_name='sheetname')
writer.save()

Refer to Append Data at the End of an Excel Sheet section in this medium article:
Using Python Pandas with Excel Sheets
(Credit to Nensi Trambadiya for the article)
Basically you'll have to first read the Excel file and find the number of rows before pushing the new data.
reader = pd.read_excel(r'master.xlsx')
df.to_excel(writer,index=False,header=False,startrow=len(reader)+1)

First read the excel file and then need to perform below method to append the rows.
import pandas as pd
from xlsxwriter import load_workbook
df = pd.DataFrame({'Name': ['abc','def','xyz','ysv'],
'Age': [08,45,32,26]})
writer = pd.ExcelWriter('master.xlsx', engine='xlsxwriter')
writer.book = load_workbook('Master.xlsx')
writer.sheets = dict((ws.title, ws) for ws in writer.book.worksheets)
reader = pd.read_excel(r'master.xlsx')
df.to_excel(writer,index=False,header=False,startrow=len(reader)+1)
writer.close()

import pandas as pd
from openpyxl import load_workbook
# new dataframe with same columns
df = pd.read_csv('combo.csv')
writer = pd.ExcelWriter('master.xlsx', engine='openpyxl')
# try to open an existing workbook
writer.book = load_workbook('master.xlsx')
# copy existing sheets
writer.sheets = dict((ws.title, ws) for ws in writer.book.worksheets)
# read existing file
reader = pd.read_excel(r'master.xlsx')
# write out the new sheet
df.to_excel(writer, index=False, header=False, startrow=len(reader) + 1)
writer.close()
Note that a Master has to be created before running the script

openpyxl not writing dataframe to excel sheet

I have some code to write a pandas dataframe to an excel sheet and for some reason it just doesn't do anything. I have used the same method previously with success.
book = load_workbook(os.path.commonpath(output)) #user is prompted for output file earlier in program
writer = pd.ExcelWriter(os.path.commonpath(output), engine = 'openpyxl')
writer.book = book
writer.sheets = dict((ws.title, ws) for ws in book.worksheets)
df.to_excel(writer, sheet_name = 'Check', startrow = writer.sheets['Check'].max_row, index = False) # this should write the df out starting at the first row that doesn't contain any data in the excel sheet.
The program runs fine, just no output to the excel sheet when I open it. Any ideas?

I believe you need a writer.save() at the end of your code!

Creating Excel sheets in same workbook in python

Need a suggestion in my code.
I have a data frame in sheet1 of workbook:
column 1 column 2
000A0000 2
000B0000 3
000A0001 5
000B0001 1
My desired result:
in sheet 2 of Workbook:
column 1 column 2
000A0000 2
000A0001 5
In sheet 3 of Workbook:
column 1 column 2
000B0000 3
000B0001 1
I have done my coding:
import pandas as pd
file="workbook.xlxs"
print(data.sheet_names)
data=data.parse("sheet1")
substrings = ['A', 'B']
T = {x: df[df['sheet1'].str.contains(x, na=False, regex=False)] for x in substrings]
for key, var in T.items():
var.to_excel(f'{key}.xlsx', index=False)
by this I can create new workbook. But I need to create new worksheet in same workbook.
Any suggestion would be appreciated.

To add sheets to the same excel file use openpyxl module as follows:
import pandas as pd
import openpyxl
#reading the sheet1 using read_excel
df = pd.read_excel('workbook.xlsx', sheet_name='Sheet1')
#creating pandas ExcelWriter object and loading the excel file using `openpyxl`
df_writer = pd.ExcelWriter('workbook.xlsx', engine='openpyxl')
excel = openpyxl.load_workbook('workbook.xlsx')
df_writer.book = excel
#checking string in column 1 and writing those to respective sheets in same workbook
for string in ['A','B']:
df[df['column 1'].str.contains(string)].to_excel(df_writer,sheet_name=string)
#saving and closing writer
writer.save()
writer.close()

to_excel would not append sheets to your existing file:
use openpyxl instead:(something like below)
import pandas
from openpyxl import load_workbook
book = load_workbook('path+filename_you_want_to_write_in.xlsx')
writer = pandas.ExcelWriter('path+filename_you_want_to_write_in.xlsx', engine='openpyxl')
writer.book = book
writer.sheets = dict((ws.title, ws) for ws in book.worksheets)
df.to_excel(writer, "Sheet_name_as_per_your_choice",index=False)
writer.save()
Also if you dynamically want to read through the sheets and not specific sheets:
f = pd.ExcelFile(file)
sheet_names = df.sheet_names
for i in list(sheet_names):
df = pd.read_excel(f,i)
This iterates through all your sheets and provides a dataframe based on the sheets.

Try using the xlsxwriter engine.
writer = pd.ExcelWriter('<< file_name >>', engine='xlsxwriter')
df.to_excel(writer, sheet_name='Sheet2')
writer.save()